Optical and photodynamic properties of carbon/TiO2 hybrid dots in different nanoscale configurations.

• Carbon dots (CDots) exploit unique properties of small carbon nanoparticles; • Carbon/semiconductor hybrid dots substantially expand the CDots platform; • Carbon/TiO 2 dots in different compositions/configurations can be designed and prepared; • The hybrid dots can be explored for different photoexcited state properties; • The hybrid dots can serve as effective photodynamic antibacterial agents. Carbon/TiO 2 hybrid dots with the general configuration of nanoscale carbon domains incorporated with TiO 2 nanoparticles of different sizes (8 and 25 nm in diameter) were prepared and characterized, and their optical and photodynamic properties were studied. The properties were found to be affected dramatically by the relative sizes and configurations of the nanoscale carbon domains and TiO 2 nanoparticles in the hybrid dots, as reflected by the observed major difference in their photodynamic inactivation of bacteria under visible light. Mechanistic implications of the results are discussed. [ABSTRACT FROM AUTHOR]